What was among the last frontier to be mapped

A) Africa

B) South Pole

C) Europe

D) North america

I'm not 100% sure this is correct but I would say that the answer is b) the south pole. Unlike most other continents that had already been mapped extensively, the coastline and geography of Antarctica was not fully understood until around the mid 19th century, and before that was amongst a part of the world that went unmapped for a while because it had not yet been properly discovered and/or recorded.